Dust Removal Arrangement for an Engine-Driven Tool

ABSTRACT

The present disclosure relates to engine-driven tool ( 1 ) comprising a rotatable work tool ( 2 ) and an engine ( 4 ) for propelling a first driving pulley ( 28 ) via a clutch wheel ( 30 ) comprised in a power transferring unit ( 27 ) and having an outer edge. The first driving pulley ( 28 ) and the clutch wheel ( 30 ) arc arranged to rotate around a common driving axis ( 38 ). The power transferring unit ( 27 ) comprises an endless drive belt ( 9 ) that is arranged propel the rotatable work tool ( 2 ) when the first driving pulley ( 28 ) is propelled. A fan arrangement ( 13 ) is arranged to convey air front a dust channel ( 11 ) formed between a shielding cover ( 8 ) and the rotatable work tool ( 2 ), and comprises a fan turbine ( 26 ) that is connected to a fan pulley ( 29 ) connected to the drive belt ( 9 ) is arranged to propel the fan pulley ( 29 ). A first overlap line ( 50 ) extends along the outer edge ( 52 ) of the clutch wheel ( 30 ), perpendicular to the extension of the common driving axis ( 38 ), the first overlap line ( 50 ) further extending via the fan turbine ( 26 ).

TECHNICAL FIELD

The present disclosure relates to an engine-driven tool that comprises arotatable work tool and an engine that is arranged to propel a firstdriving pulley via a clutch wheel comprised in a power transferringunit. The engine-driven tool further comprises a shielding cover that isarranged to shield a part of the rotatable work tool.

BACKGROUND

Many motor tools such as engine-driven handheld cutting machines havesaw blades which may be circular or ring-shaped. Such a cutting machinemay be used for cutting hard materials such as concrete or rock, wherethe cutting procedure may result in the creation of dust. For exampleconcrete dust is unhealthy to breathe and also impairs visions, and itis desired to minimize the creations of such dust that freely may expandin the air. Such free concrete dust that finds its way into the engineof the tool drastically affects the engine in a negative way, may causeundesirable health effects and generally pollutes the environment.

Many tools of the above type or for this purpose equipped with a watersupply, where a flow of water is directed towards the saw blade in sucha way that a large quantity of the dust is mixed with the water and thusretained and kept from expanding in the air.

The flow of water is preferably held at a minimum while maintaining aproper function, since the water normally has to be taken care of at theworking site, more water than necessary is undesirable. At some workingsites, a demand for cleanliness, or shortage of water, results in thatsuch a water supply is undesired. For this purpose, many types of dustremoval systems of vacuum cleaner type have been developed. Some of themhave an integrated fan for propelling air into a dust hose that guidesundesired dust particles to a remote dust container. These fans arenormally propelled by means of a transmission arrangement that isconnected to the cutting machine's main engine, and comprises one ormore drive belts or geared transmissions, for example as described inU.S. Pat. No. 6,039,037. It is desired to obtain a less complicated andversatile dust removal arrangement for an engine-driven tool such as apower cutter.

The dust that is to be removed is first often collected in a shieldingcover that is arranged to shield a part of the saw blade, where theshielding cover comprises an outlet that is connected to the fan forremoving the dust that has been collected in the shielding cover. It istherefore desired that as much dust as possible is collected in theshielding cover when operating an engine-driven tool such as a powercutter, avoiding dust to be released in surrounding air. WO 2014127037discloses a dust shroud that is configured with either one or twoextending and telescoping lower rigid jaws, but a more efficientarrangement is desired.

SUMMARY

The object of the present disclosure is to provide a dust removalarrangement for an engine-driven tool that is less complicated andversatile compared to prior art, where a reliable removal of dust isprovided, minimizing dust that is released in surrounding air.

This object is achieved by means of an engine-driven tool comprising arotatable work tool having a center and a circumference and an enginethat is arranged to propel the rotatable work tool. The engine-driventool further comprises a shielding cover that is arranged to shield apart of the rotatable work tool and a first swiveling part that isattached by means of a first swivel attachment and partly extends eitherinside or outside the shielding cover, allowing the first swiveling partto pivot around a first swivel axis that crosses the rotatable work toolcloser to the center of the rotatable work tool than the circumferenceof the work tool. The engine-driven tool comprises a second swivelingpart that is attached to the first swiveling part and partly extendseither inside or outside the first swiveling part. The second swivelingpart is attached to the first swiveling part by means of a second swivelattachment allowing the second swiveling part to pivot around a secondswivel axis that runs outside the circumference of the rotatable worktool, allowing the swiveling parts to self-adjust to a work surface suchthat the amount of dust that enters the shielding cover is increased.

According to an example, the second swiveling part comprises a slot thatadmits clearance for the saw rotatable work tool.

According to another example, the shielding cover comprises a dustchannel that is formed between the shielding cover and the rotatablework tool. A dust hose is arranged to at least indirectly connect thedust channel to a dust container. A fan arrangement is arranged toconvey air from the dust channel into the dust container via the dusthose.

According to another example, the second swivel attachment have attachedsupporting wheels that enable the engine-driven tool to run on thesesupporting wheels when in operation.

According to another example, the engine-driven tool comprises a firstspring means that is arranged to expose the first swiveling part to afirst spring force and a second spring means that is arranged to exposethe second swiveling part to a second spring force. Each spring force isarranged to extend the corresponding swiveling part away from theshielding cover.

According to another example, the first swiveling part is attached to asaw blade bearing frame by means of the first swivel attachment.

This object is also achieved by an engine-driven tool comprising arotatable work tool and an engine that is arranged to propel a firstdriving pulley comprised in a power transferring unit that comprises anendless drive belt that is arranged to at least indirectly propel therotatable work tool when the first driving pulley is propelled. Theengine-driven tool further comprises a shielding cover that is arrangedto shield a part of the rotatable work tool, and a dust channel that isformed between the shielding cover and the rotatable work tool. The dustchannel is at least indirectly connected to a fan arrangement that isarranged to convey air from the dust channel and comprises a fan turbinethat is connected to a fan pulley comprised in the power transferringunit. The drive belt is arranged to propel the fan pulley. When the fanpulley is in a tensioned state, the drive belt is tensioned and arrangedto drive both the fan pulley and the rotatable work tool, and when thefan pulley is in a released state, the tension of the drive belt isreleased.

According to an example, the engine-driven tool comprises a dust hosethat is arranged to connect the dust channel to a dust container, wherethe fan arrangement is arranged to convey air from the dust channel intothe dust container via the dust hose.

This object is also achieved by an engine-driven tool comprising arotatable work tool and an engine that is arranged to propel a firstdriving pulley via a clutch wheel comprised in a power transferringunit. The first driving pulley and the clutch wheel are arranged torotate around a common driving axis, and the clutch wheel has an outeredge that is farthest from the driving pulley along the common drivingaxis. The power transferring unit comprises an endless drive belt thatis arranged to at least indirectly propel the rotatable work tool whenthe first driving pulley is propelled. The engine-driven tool furthercomprises a shielding cover that is arranged to shield a part of therotatable work tool, and a dust channel that is formed between theshielding cover and the rotatable work tool. The dust channel is atleast indirectly connected to a fan arrangement that is arranged toconvey air from the dust channel and comprises a fan turbine that isconnected to a fan pulley comprised in the power transferring unit. Thedrive belt is arranged to propel the fan pulley. A first overlap lineextends along the outer edge of the clutch wheel, perpendicular to theextension of the common driving axis, the first overlap line furtherextending via the fan turbine.

Other examples are disclosed in the dependent claims.

A number of advantages are obtained by means of the present disclosure.Mainly, a transmission arrangement for propelling a dust removal fan isprovided having an integrated tensioning functionality. Furthermore, amore reliable collecting of dust is provided, minimizing dust that isreleased in surrounding air.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will now be described more in detail withreference to the appended drawings, where:

FIG. 1 shows a side view of a hand-held power cutter with swivelingparts in a first position;

FIG. 2 shows a side view of a hand-held power cutter with swivelingparts in a second position;

FIG. 3 shows a schematic front view of a part of the saw blade in theshielding cover;

FIG. 4 shows a side view of the saw blade in the shielding cover;

FIG. 5 shows a perspective top view of the saw blade in the shieldingcover;

FIG. 6 shows a perspective front view of a fan arrangement with a cover;

FIG. 7 shows a perspective front view of a fan arrangement without acover;

FIG. 8 shows a perspective front view of a first example of a powertransferring unit with a belt in a tensioned state;

FIG. 9 shows a perspective front view of the first example of a powertransferring unit with a drive belt in a released state;

FIG. 10 shows an upper sectional view of FIG. 8;

FIG. 11 shows a perspective front view of a second example of a powertransferring unit with a belt in a tensioned state; and

FIG. 12 shows a perspective front view of the second example of a powertransferring unit with a drive belt in a released state.

DETAILED DESCRIPTION

FIG. 1 and FIG. 2 shows respective side views of a hand-held powercutter 1 with a circularly shaped saw blade 2, for example suitable tocut through concrete. The saw blade 2 has a center 16 and acircumference 17 (only schematically indicated). The power cutter 1comprises a casing 3 at least partly enclosing a combustion engine 4,where the casing 3 in turn comprises a first handle part 5 from which apower/throttle switch 6 a and corresponding switch lock 6 b isaccessible. The power cutter 1 further comprises a second handle part 7that runs in an arcuate shape over the casing 3, the second handle part7 being attached to the casing 3 via means that attenuate vibrations ina well-known manner.

The power cutter 1 comprises a shielding cover 8 that is arranged toshield a part of the saw blade 2. The saw blade 2 is connected to theengine 4 via a power transferring unit 27 that comprises a powertransferring means 9 that is covered by a power transfer cover 10. Thepower transferring means 9 is according to some aspects either in theform of an endless drive belt or a geared transmission. Here, a drivebelt 9 is shown, driving a second drive pulley 33 that in turn isarranged to propel the saw blade 2. The power transferring unit 27 canalso be referred to as a clutch side crank case.

A dust channel 11 is formed between the shielding cover 8 and the sawblade 2, where a dust pipe 12 is connected between an upper part of theshielding cover 8 and a fan arrangement 13 that is adapted to lower theair pressure at the dust pipe 12 such that air is conveyed from the dustpipe 12 and further into a hose 14 that is connected between the fanarrangement 13 and a dust container 15. The dust container 15 isarranged to receive the dust that has been propelled from the dustchannel 11 by means of the fan arrangement 13 such that an operationthat is similar or the same as the operation of a vacuum cleaner isobtained. It is to be noted that the dust container 15 only isschematically indicated for describing a principle, not being shown inactual size and configuration.

When the power cutter 1 is in operation and the saw blade 2 for exampleis cutting through concrete, a lot of concrete dust is formed. By meansof the fan arrangement 13 and the dust hose 14, the concrete dust isconveyed from the dust channel 11 in the shielding cover 8 to the dustcontainer 15. In order to obtain a proper functionality, it is desiredthat the amount of dust that escapes the dust channel 11 in theshielding cover 8 is minimized, and therefore a first swiveling part 18is attached to the shielding cover 8 such that a self-adjusting coverbetween the power cutter 1 and a work surface 19, here schematicallyindicated with a dash-dotted line, is obtained. With reference also toFIG. 3, showing a schematic front view of a part of the saw blade in theshielding cover, the first swiveling part 18 is attached to theshielding cover 8 by means of a first swivel attachment 20 allowing thefirst swiveling part 18 to pivot around a first swivel axis 21 thatcrosses the saw blade 2 closer to the center 16 of the saw blade 2 thanthe circumference 17 of the saw blade 2. The first swiveling part 18 canbe attached to any suitable part such as a saw blade bearing frame 49 asshown in FIG. 1 and FIG. 2. Such a saw blade bearing frame 49 can be aseparate part, or integrated with the shielding cover 8. In FIG. 3, thefirst swiveling part 18 is shown to be attached to the shielding cover8.

According to the present disclosure, a second swiveling part 22 isattached to the first swiveling part 18 such that an improvedself-adjusting combined cover between the power cutter 1 and the worksurface 19 is obtained. The second swiveling part 22 is attached to thefirst swiveling part 18 by means of a second swivel attachment 23allowing the second swiveling part 22 to pivot around a second swivelaxis 24 that runs outside the circumference 17 of the saw blade 2. Thesecond swiveling part 22 comprises a slot 47 that admits clearance forthe saw blade 2.

Both swiveling parts 18, 22 have a pie-shaped appearance, where thefirst swiveling part 18 partly extends inside the shielding cover 8, andwhere the second swiveling part 22 extends inside the first swivelingpart 18, such that each swiveling part 18, 22 has a certain degree ofexposure that changes as each swiveling part 18, 22 pivot around itscorresponding swivel axis 21, 24. As a result of this the firstswiveling part 18 has first clearance angle φ and the second swivelingpart 22 has second clearance angle θ.

Both swiveling parts 18, 22 self-adjust to the work surface 19 such thatthe amount of dust that escapes the dust channel 11 in the shieldingcover 8 is minimized, resulting in a minimized amount of dust that isreleased into surrounding air. In FIG. 1, the swiveling parts 18, 22have a certain position due to the position of the work surface 19, andin FIG. 2 the swiveling parts 18, 22 have another position where theclearance angles φ′, θ′ have decreased due to a changed position of thework surface 19′.

With reference to FIG. 4, showing a detail side view of the saw blade 2in the shielding cover 8 without the second drive wheel, the saw bladebearing frame 49 and the dust pipe, and FIG. 5, showing a detailperspective view of the saw blade 2 in the shielding cover 8 without thefirst swivel attachment 20 and the saw blade bearing frame 49, there isa first spring means 41 that is arranged to expose the first swivelingpart 18 to a first spring force and a second spring means 42 that isarranged to expose the second swiveling part 22 to a second springforce. The swiveling parts 18, 22 are thus spring-loaded, such that thecorresponding spring force is arranged to maximize the correspondingclearance angle φ, θ.

The second swiveling part 22 is retained by means of the stop pin 43.The second spring means 42 is retained by a first rim 44, formed on thefirst swiveling part 18 and a second rim 45 formed on the secondswiveling part 22. These rims 44, 45 also provide enforcements for theswiveling parts 18, 22, conferring an enhanced rigidity. The secondswiveling part 22 comprises a shaped edge 46 that is arranged to pivotinto the shielding cover 8, where its shape is optimized for enablingmaximal possible pivoting into the shielding cover 8.

According to some aspects, the first swiveling part 18 partly extendsoutside the shielding cover 8, and according to some aspects, the secondswiveling part 22 partly extends outside the first swiveling part 18. Ingeneral terms this means that the second swiveling part 22 is arrangedto extend along the circumference 17 of the saw blade 2 to a largerextent than the first swiveling part 18, while the first swiveling part18 is arranged to extend radially from the center 16 of the saw blade 2than the second swiveling part 22.

If the first swiveling part 18 partly extends outside the shieldingcover 8, and the second swiveling part 22 partly extends inside thefirst swiveling part 18, the first swiveling part 18 will not beconcealed and then has a constant clearance angle. If the secondswiveling part 22 partly extends outside the first swiveling part 18,the second swiveling part 22 will not be concealed and then has aconstant clearance angle.

According to some aspects, as shown in FIG. 1, FIG. 2 and FIG. 4, thedust channel 11 is connected to the dust pipe 12 via an aperture 35,where the aperture 35 is positioned outside the circumference 17 of thesaw blade 2. In view of the distance that the dust which forms duringsawing operation is propelled via the swiveling parts 18, 22, and thenormal rotational speed of the saw blade during operation, the aperture35 has an advantageous position in order to enable as much dust aspossible to be removed from the dust channel 11 via the dust pipe 12.Furthermore, in order to even more increase the amount of dust that isremoved from the dust channel 11 via the dust pipe 12, a separating wall37 is formed in shielding cover 8 with a slot aperture for the saw blade2. The separating wall 37 prevents dust that has not immediately beenconveyed into the dust pipe 12 from following the motion of the sawblade 12, escaping the shielding cover 8 and getting into theenvironment.

FIG. 6 shows the fan arrangement 13 with a cover 25, and FIG. 7 showsthe fan arrangement 13 without the cover 25, where a fan turbine 26 isplaced and arranged to be propelled for conveying dust from the dustpipe 12 and further into the hose 14 as shown in FIG. 1 and FIG. 2. Forthis purpose, the fan turbine 26 comprises a plurality of fan blades 53as shown in FIG. 7. The cover 25 has an outer surface 55 that isfarthest from the fan turbine 26.

FIG. 8 and FIG. 9 show respective perspective front views of the powertransferring unit 27 of the power cutter where the power transfer cover10 and the fan arrangement 13 are removed. A first driving pulley 28 isconnected to an endless drive belt 9 that here constitutes the powertransferring means, where the drive belt is tensioned against a fanpulley 29 that is arranged to be connected to the fan turbine 26 whenthe fan arrangement 13 is mounted. The fan pulley 29 is furthermorearranged to propel the fan turbine 26 when the drive belt 9 rotates thefan pulley 29. The drive belt 9 is arranged to propel the second drivingpulley 33 which is arranged to propel the saw blade 2 in a well-knownmanner; for example directly or via a transmission.

The first driving pulley 28 is connected to the engine via a clutchwheel 30 and an engine gear arrangement (not shown). For reasons ofclarity, well-known clutch parts that normally are positioned within theclutch wheel 30 and are arranged to confer transmission between theclutch wheel 30 and the first driving pulley 28 at certain rotationalvelocities are not shown. These clutch parts normally work bycentrifugal forces and are commonly used in tools of this kind. Theclutch wheel 30 and the first driving pulley 28 are arranged to rotatearound a common driving axis 38, where the clutch wheel 30 has an outeredge 52 that is farthest from the driving pulley 28 along the commondriving axis 38.

According to some aspects, the rotational speed of the engine is gearedto a lower rotational speed at the first driving pulley 28 by means ofthe engine gear arrangement, and then the rotational speed of the asecond driving pulley 33 is geared to a lower rotational speed at thesaw blade 2.

This means that during operation of the power cutter 1, the engine 4 isarranged to propel the first driving pulley 28 via the clutch wheel 30,where the first driving pulley 28 in turn drives the drive belt 9. Whenthe drive belt is moving, it also rotates the fan pulley 29, bringingthe fan turbine 26 into motion and thus the fan arrangement 13 intooperation. By choosing a suitable diameter of the fan pulley 29, adesired rotational speed of the fan pulley 29, and thus of the fanturbine 26, during normal operation of the power cutter 1 is obtained.

With reference also to FIG. 10, showing an upper sectional view of FIG.8 with the fan arrangement 13 mounted, in order to obtain a reliablepower transmission between the belt and the pulleys 28, 29, 33, eachpulley 28, 29, 33 comprises teeth 31, 32, 34 that engage correspondingbelt teeth 48 (a few indicated for reason of clarity).

According to another aspect of the present disclosure with continuedreference to FIG. 10, when mounted, the fan arrangement 13 is arrangedto at least partly overlap the clutch wheel 30 along a directionparallel to the extension of the common driving axis 38. This compactmounting arrangement provides a stable handling of the power cutter 1with a side-mounted fan arrangement 13.

More in detail, in FIG. 10, there is a first overlap line 50 and asecond overlap line 51, where the overlap lines 50, 51 are mutuallyparallel and extend perpendicular to the extension of the common drivingaxis 38. The first overlap line 50 extends along the outer edge 52 ofthe clutch wheel 30, and the second overlap line 51 extends between thefan turbine 26 and the drive belt 9. The first overlap line 50 extendsvia the fan turbine 26, running through a plurality of fan blades 53.

There is an overlap distance 54 between the first overlap line 50 andthe second overlap line 51, where the overlap distance 54 exceeds zero.There is also a protrusion distance 56 between the outer surface 55 ofthe cover 25 and the first overlap line 50. According to some aspects,the protrusion distance 56 is minimized.

The fan turbine has a turbine height 57; in FIG. 10 the turbine height57 extends parallel to the extension of the common driving axis 38.According to some aspects, the protrusion distance 56 falls below theturbine height 57.

Furthermore, according to yet another aspect of the present disclosure,the fan pulley 29 is adjustable and arranged for tensioning the drivebelt 9. In FIG. 8, the fan pulley 29 is adjusted such that the drivebelt 9 is tensioned and ready for operation, and in FIG. 9, the fanpulley 29 is adjusted such that the drive belt 9 is released fromtension, a suitable positon if, for example, the drive belt should bereplaced. Here, the drive belt 9 is running on an outside of the fanpulley 29, such that when the fan pulley 29 is moved away from a part ofthe drive belt 9 that is extending between the first driving pulley 28and the saw blade, and is not intended to be in contact with the fanpulley 29, the drive belt 9 is tensioned.

The drive belt 9 could run at any side of the fan pulley 29, as shown inFIG. 11 and FIG. 12. In FIG. 11, the fan pulley 29 is adjusted such thatthe drive belt 9 is tensioned and ready for operation, and in FIG. 12,the fan pulley 29 is adjusted such that the drive belt 9 is releasedfrom tension. Here, the drive belt 9 is running on an inside of the fanpulley 29, such that when the fan pulley 29 is moved away from a part ofthe drive belt 9 that is extending between the first driving pulley 28and the saw blade, and is not intended to be in contact with the fanpulley 29, the drive belt 9 is released from tension.

The present disclosure is not limited to the above examples, but mayvary freely within the scope of the appended claims. For example, thehand-held power cutter 1 with a ring-shaped saw blade 2 may be any typeof engine-driven tool with a rotatable work tool such as a saw blade, acircular saw blade or a ring saw blade, where dust removal is desired.Only some items of the engine-driven tool in the example have beendescribed, the engine-driven tool in itself being of a well-known kind.The engine can either be a combustion engine or an electric motor.

With reference to FIG. 8, FIG. 9, FIG. 10, FIG. 11 and FIG. 12, the belt9 can be tensioned by having an adjustable power transferring unit 27,where a first frame part 39 and a second frame part 40 are slidablymovable in relation to each other in a previously well-known manner.This tensioning arrangement can be the only available, the fan pulley 29being fixed. Alternatively, The adjustable fan pulley 29 as describedabove can also be the only tensioning arrangement available. Acombination of both is also conceivable. The tensioning procedure may inall cases be performed in any conventional manner. For example by meansof a tensioning screw assembly that is arranged to separate adequateparts when tensioning, or by means of a swiveling cam that is arrangedto separate adequate parts when tensioning. These and other sucharrangements are well-known in the art.

According to some aspects, the fan arrangement 13 is connected directlyto the dust channel 11; alternatively, the dust pipe 12 is comprised inthe fan arrangement 13.

According to some aspects, the fan arrangement 13 comprises a dustcontainer.

According to some aspects, the fan arrangement 13 is arranged to blowthe collected dust into the environment away from a person operating thepower cutter, possibly via a dust hose part.

When a drive belt 9 is used, according to some aspects the drive belt isarranged to propel the saw blade via a gear transmission.

For the embodiments with reference to FIGS. 1-3, a fan arrangement 13 isshown positioned on the power cutter, and can then be powered asdescribed in the embodiments with reference to FIGS. 4-8. Generally, forthe embodiments with reference to FIGS. 1-3, there need not be any fanarrangement at all, the swiveling parts 18, 22 merely being arranged tokeep dust within the shielding cover 8, or to just have it disposed inany convenient direction by a pipe, tube, opening and/or hose, suitablyaway from a person operating the power cutter.

For the embodiments with reference to FIGS. 6-12, the swiveling parts18, 21 may of course also be applied.

The shielding cover 8 has two sides, one at each side of the saw blade2. In FIG. 3, the first swivel attachment 20 is shown as a pin attachedto one side of the shielding cover 8. Of course, there could be two suchpins, one at each side. The second swivel attachment 23 is here shown asa shaft running between both sides of the shielding cover. Here, one ortwo pins as described for the first swivel attachment 20 could be usedinstead.

As shown with dashed lines in FIG. 1, FIG. 2 and FIG. 3, supportingwheels 36 may be attached to the second swivel attachment 23, allowingthe power cutter to run on these supporting wheels 36 when in operation.

The drive belt 9 does not have to be arranged to propel the saw blade 2via a gear arrangement, but may be arranged to propel the second drivepulley 33 which in turn is directly connected to the saw blade 2 withoutany gears.

If a fan arrangement is used for disposing of the dust for theembodiments with reference to FIGS. 1-3, it may be positioned anywhere,for example it can be comprised in the dust container 15 at the end ofthe dust hose 14. The fan can be electrically powered, according to someaspects by an electrical current that is generated in the power cutter.

Generally, the present disclosure relates to an engine-driven tool 1comprising a rotatable work tool 2 having a center 16 and acircumference 17, an engine 4 that is arranged to propel the rotatablework tool 2, where the engine-driven tool 1 further comprises ashielding cover 8 that is arranged to shield a part of the rotatablework tool 2 and a first swiveling part 18 that is attached by means of afirst swivel attachment 20 and partly extends either inside or outsidethe shielding cover 8, allowing the first swiveling part 18 to pivotaround a first swivel axis 21 that crosses the rotatable work tool 2closer to the center 16 of the rotatable work tool 2 than thecircumference 17 of the rotatable work tool 2. The engine-driven tool 1comprises a second swiveling part 22 that is attached to the firstswiveling part 18 and partly extends either inside or outside the firstswiveling part 18, where the second swiveling part 22 is attached to thefirst swiveling part 18 by means of a second swivel attachment 23,allowing the second swiveling part 22 to pivot around a second swivelaxis 24 that runs outside the circumference 17 of the rotatable worktool 2, enabling the swiveling parts 18, 22 to self-adjust to a worksurface 19 such that the amount of dust that enters the shielding cover8 is increased.

According to an example, the second swiveling part 22 comprises a slot47 that admits clearance for the saw rotatable work tool 2.

According to an example, both swiveling parts 18, 22 have a respectivepie-shaped appearance.

According to an example, the shielding cover 8 comprises a dust channel11 that is formed between the shielding cover 8 and the rotatable worktool 2, where a dust hose 14 is arranged to at least indirectly connectthe dust channel 11 to a dust container 15, where a fan arrangement 13is arranged to convey air from the dust channel 11 into the dustcontainer 15 via the dust hose 14.

According to an example, the engine 4 is arranged to propel a firstdriving pulley 28 comprised in a power transferring unit 27, where thepower transferring unit 27 comprises an endless drive belt 9 that isarranged to at least indirectly propel the rotatable work tool 2 whenthe first driving pulley 28 is propelled, where the fan arrangement 13comprises a fan turbine 26 that is connected to a fan pulley 29comprised in the power transferring unit 27, where the drive belt 9 isarranged to propel the fan pulley 29 and the fan pulley 29 in turn isarranged to propel the fan turbine 26.

According to an example, the each pulley 28, 29 comprises teeth 31, 32that engage corresponding belt teeth 48.

According to an example, when the fan pulley 29 is in a tensioned state,the drive belt 9 is tensioned and arranged to drive both the fan pulley29 and the rotatable work tool 2, and when the fan pulley 29 is in areleased state, the tension of the drive belt 9 is released.

According to an example, the engine 4 is arranged to propel a firstdriving pulley 28 via a clutch wheel 30 comprised in a powertransferring unit 27, where the first driving pulley 28 and the clutchwheel 30 are arranged to rotate around a common driving axis 38, andwhere the clutch wheel 30 has an outer edge 52 that is farthest from thedriving pulley 28 along the common driving axis 38, where furthermore afirst overlap line 50 extends along the outer edge 52 of the clutchwheel 30, perpendicular to the extension of the common driving axis 38,the first overlap line 50 further extending via the fan turbine 26.

According to an example, the engine 4 is either constituted by acombustion engine or by an electric motor.

According to an example, the second swivel attachment 23 have attachedsupporting wheels 36 that enable the engine-driven tool 1 to run onthese supporting wheels 36 when in operation.

According to an example, the engine-driven tool 1 comprises a firstspring means 41 that is arranged to expose the first swiveling part 18to a first spring force and a second spring means 42 that is arranged toexpose the second swiveling part 22 to a second spring force, where eachspring force is arranged to extend the corresponding swiveling part 18,22 away from the shielding cover 8.

According to an example, the second spring means 42 is retained by afirst rim 44, formed on the first swiveling part 18 and a second rim 45formed on the second swiveling part 22, where these rims 44, 45 arearranged to also provide an enhanced rigidity for the swiveling parts18, 22.

According to an example, the second swiveling part 22 comprises a shapededge 46 that is arranged to pivot into the shielding cover 8, where saidedge 46 has a shape that is optimized for enabling maximal possiblepivoting into the shielding cover 8.

According to an example, the first swiveling part 18 is attached to asaw blade bearing frame 49 by means of the first swivel attachment 20.

Generally, the present disclosure also relates to an engine-driven tool1 comprising a rotatable work tool 2 and an engine 4 that is arranged topropel a first driving pulley 28 comprised in a power transferring unit27, where the power transferring unit 27 comprises an endless drive belt9 that is arranged to at least indirectly propel the rotatable work tool2 when the first driving pulley 28 is propelled, where the engine-driventool 1 further comprises a shielding cover 8 that is arranged to shielda part of the rotatable work tool 2, and a dust channel 11 that isformed between the shielding cover 8 and the rotatable work tool 2,which dust channel 11 at least indirectly is connected to a fanarrangement 13, which fan arrangement 13 is arranged to convey air fromthe dust channel 11 and comprises a fan turbine 26 that is connected toa fan pulley 29 comprised in the power transferring unit 27, where thedrive belt 9 is arranged to propel the fan pulley 29. When the fanpulley 29 is in a tensioned state, the drive belt 9 is tensioned andarranged to drive both the fan pulley 29 and the rotatable work tool 2,and when the fan pulley 29 is in a released state, the tension of thedrive belt 9 is released.

According to an example, the engine-driven tool 1 comprises a dust hose14 that is arranged to connect the dust channel 11 to a dust container15, where the fan arrangement 13 is arranged to convey air from the dustchannel 11 into the dust container 15 via the dust hose 14.

According to an example, the engine 4 is arranged to propel a firstdriving pulley 28 via a clutch wheel 30 comprised in a powertransferring unit 27, where the first driving pulley 28 and the clutchwheel 30 are arranged to rotate around a common driving axis 38, andwhere the clutch wheel 30 has an outer edge 52 that is farthest from thedriving pulley 28 along the common driving axis 38, where furthermore afirst overlap line 50 extends along the outer edge 52 of the clutchwheel 30, perpendicular to the extension of the common driving axis 38,the first overlap line 50 further extending via the fan turbine 26.

According to an example, the each pulley 28, 29 comprises teeth 31, 32that engage corresponding belt teeth 48.

Generally, the present disclosure also relates to an engine-driven tool1 comprising a rotatable work tool 2 and an engine 4 that is arranged topropel a first driving pulley 28 via a clutch wheel 30 comprised in apower transferring unit 27, where the first driving pulley 28 and theclutch wheel 30 are arranged to rotate around a common driving axis 38,and where the clutch wheel 30 has an outer edge 52 that is farthest fromthe driving pulley 28 along the common driving axis 38, wherefurthermore the power transferring unit 27 comprises an endless drivebelt 9 that is arranged to at least indirectly propel the rotatable worktool 2 when the first driving pulley 28 is propelled, where theengine-driven tool 1 further comprises a shielding cover 8 that isarranged to shield a part of the rotatable work tool 2, and a dustchannel 11 that is formed between the shielding cover 8 and therotatable work tool 2, which dust channel 11 at least indirectly isconnected to a fan arrangement 13 that is arranged to convey air fromthe dust channel 11 and comprises a fan turbine 26 that is connected toa fan pulley 29 comprised in the power transferring unit 27, where thedrive belt 9 is arranged to propel the fan pulley 29. A first overlapline 50 extends along the outer edge 52 of the clutch wheel 30,perpendicular to the extension of the common driving axis 38, the firstoverlap line 50 further extending via the fan turbine 26.

According to an example, when the fan pulley 29 is in a tensioned state,the drive belt 9 is tensioned and arranged to drive both the fan pulley29 and the rotatable work tool 2, and when the fan pulley 29 is in areleased state, the tension of the drive belt 9 is released.

According to an example, the engine-driven tool 1 comprises a dust hose14 that is arranged to connect the dust channel 11 to a dust container15, where the fan arrangement 13 is arranged to convey air from the dustchannel 11 into the dust container 15 via the dust hose 14.

According to an example, each pulley 28, 29 comprises teeth 31, 32 thatengage corresponding belt teeth 48.

According to an example, there is a second overlap line 51 that extendsbetween the fan turbine 26 and the drive belt 9, perpendicular to theextension of the common driving axis 38, where an overlap distance 54 isformed between the first overlap line 50 and the second overlap line 51,where the overlap distance 54 exceeds zero.

That which is claimed is:
 1. An engine-driven tool comprising arotatable work tool, having a center and a circumference, and an enginethat is arranged to propel the rotatable work tool, wherein theengine-driven tool further comprises a shielding cover that is arrangedto shield a part of the rotatable work tool, and a first swiveling partthat is attached by a first swivel attachment and partly extends eitherinside or outside the shielding cover, allowing the first swiveling partto pivot around a first swivel axis that crosses the rotatable work toolcloser to the center of the rotatable work tool than the circumferenceof the rotatable work tool, wherein the engine-driven tool comprises asecond swiveling part that is attached to the first swiveling part andpartly extends either inside or outside the first swiveling part,wherein the second swiveling part is attached to the first swivelingpart by a second swivel attachment, allowing the second swiveling partto pivot around a second swivel axis that runs outside the circumferenceof the rotatable work tool, enabling the first and second swivelingparts to self-adjust to a work surface such that the amount of dust thatenters the shielding cover is increased.
 2. The engine-driven toolaccording to claim 1, wherein the shielding cover comprises a dustchannel that is formed between the shielding cover and the rotatablework tool, wherein a dust hose is arranged to at least indirectlyconnect the dust channel to a dust container, where a fan arrangement isarranged to convey air from the dust channel into the dust container viathe dust hose.
 3. The engine-driven tool according to claim 2, whereinthe engine is arranged to propel a first driving pulley comprised in apower transferring unit, wherein the power transferring unit comprisesan endless drive belt that is arranged to at least indirectly propel therotatable work tool when the first driving pulley is propelled, whereinthe fan arrangement comprises a fan turbine that is connected to a fanpulley comprised in the power transferring unit, wherein the drive beltis arranged to propel the fan pulley and the fan pulley in tune isarranged to propel the fan turbine.
 4. The engine-driven tool accordingto claim 3, wherein each of the fan pulley and the first driving pulleycomprises teeth that engage corresponding belt teeth.
 5. Theengine-driven tool according to claim 3, wherein when the fan pulley isin a tensioned state, the drive belt is tensioned and arranged to driveboth the fan pulley and the rotatable work tool, and when the fan pulleyis in a released state, the tension of the drive belt is released. 6.The engine-driven tool according to claim 3, wherein the engine isarranged to propel a first driving pulley via a clutch wheel comprisedin a power transferring unit, wherein the first driving pulley and theclutch wheel are arranged to rotate around a common driving axis, andwherein the clutch wheel has an outer edge that is farthest from thedriving pulley along the common driving axis, wherein furthermore afirst overlap line extends along the outer edge of the clutch wheel,perpendicular to an extension of the common driving axis, the firstoverlap line further extending via the fan turbine.
 7. An engine-driventool comprising a rotatable work tool and an engine that is arranged topropel a first driving pulley comprised in a power transferring unit,wherein the power transferring unit comprises an endless drive belt thatis arranged to at least indirectly propel the rotatable work tool whenthe first driving pulley is propelled, wherein the engine-driven toolfurther comprises a shielding cover that is arranged to shield a part ofthe rotatable work tool, and a dust channel that is formed between theshielding cover and the rotatable work tool, the dust channel is atleast indirectly is connected to a fan arrangement, the fan arrangementis arranged to convey air from the dust channel and comprises a fanturbine that is connected to a fan pulley comprised in the powertransferring unit, wherein the drive belt is arranged to propel the fanpulley, wherein when the fan pulley is in a tensioned state, the drivebelt is tensioned and arranged to drive both the fan pulley and therotatable work tool, and when the fan pulley is in a released state,tension of the drive belt is released.
 8. The engine-driven toolaccording to claim 7, wherein the engine-driven tool comprises a dusthose that is arranged to connect the dust channel to a dust container,wherein the fan arrangement is arranged to convey air from the dustchannel into the dust container via the dust hose.
 9. The engine-driventool according to claim 7, wherein the engine is arranged to propel afirst driving pulley via a clutch wheel comprised in a powertransferring unit, wherein the first driving pulley and the clutch wheelare arranged to rotate around a common driving axis, and wherein theclutch wheel has an outer edge that is farthest from the driving pulleyalong the common driving axis, wherein furthermore a first overlap lineextends along the outer edge of the clutch wheel, perpendicular to theextension of the common driving axis, the first overlap line furtherextending via the fan turbine.
 10. The engine-driven tool according toclaim 7, wherein each of the fan pulley and the first driving pulleycomprises teeth that engage corresponding belt teeth.
 11. Anengine-driven tool comprising a rotatable work tool and an engine thatis arranged to propel a first driving pulley via a clutch wheelcomprised in a power transferring unit, wherein the first driving pulleyand the clutch wheel are arranged to rotate around a common drivingaxis, and wherein the clutch wheel has an outer edge that is farthestfrom the driving pulley along the common driving axis, whereinfurthermore the power transferring unit comprises an endless drive beltthat is arranged to at least indirectly propel the rotatable work toolwhen the first driving pulley is propelled, where the engine-driven toolfurther comprises a shielding cover that is arranged to shield a part ofthe rotatable work tool, and a dust channel that is formed between theshielding cover and the rotatable work tool, the dust channel is atleast indirectly is connected to a fan arrangement that is arranged toconvey air from the dust channel and comprises a fan turbine that isconnected to a fan pulley comprised in the power transferring unit,wherein the drive belt is arranged to propel the fan pulley, wherein afirst overlap line extends along the outer edge of the clutch wheel,perpendicular to an extension of the common driving axis, the firstoverlap line further extending via the fan turbine.
 12. Theengine-driven tool according to claim 11, wherein when the fan pulley isin a tensioned state, the drive belt is tensioned and arranged to driveboth the fan pulley and the rotatable work tool, and when the fan pulleyis in a released state, tension of the drive belt is released, andwherein the engine-driven tool comprises a dust hose that is arranged toconnect the dust channel to a dust container, wherein the fanarrangement is arranged to convey air from the dust channel into thedust container via the dust hose.
 13. The engine-driven tool accordingto claim 11, wherein each of the fan pulley and the first driving pulleycomprises teeth that engage corresponding belt teeth, and Wherein thereis a second overlap line that extends between the fan turbine and thedrive belt, perpendicular to the extension of the common driving axis,wherein an overlap distance is formed between the first overlap line andthe second overlap line, wherein the overlap distance exceeds zero.